DENIERS SAY:

An extra 2 degrees of warming? How bad could that be?

SCIENCE SAYS:

Even a global temperature rise of 2 degrees Celsius will disrupt our lives and challenge our ability to cope.

The world has warmed about 1.5 degrees Fahrenheit since 1880 (that's 0.8 degrees Celsius). That may not sound like much, but we’re already starting to see what a warmer world has in store for us. Intense rainstorms, severe droughts and heat waves are becoming more frequent. Rising seas are damaging homes near the water. Some populations of animals are starting to die out. And that’s just 1.5 degrees! Now consider what could happen if we do nothing to limit the pollution that’s causing global warming. The best available estimates say the Earth will warm another 3 to 7 degrees Fahrenheit by 2100 (roughly 2 to 4 degrees Celsius). In other words, the more we pollute, the worse things will get.

More info from The Climate Reality Project

Since 1880, the world has warmed about 0.8 degrees Celsius, or about 1.5 degrees Fahrenheit.

Doesn’t sound like much, does it?

Of course, that’s the average temperature increase for the entire planet. Averages tend to hide important detail. For instance, the murder rate in the American West declined 0.1% between 2010 and 2011. But that’s probably not too comforting to the residents of San Jose, California, where the murder rate nearly doubled over the same period. Similarly, some parts of the world are warming much faster than the global average — including Arizona, which since 1970 has been warming more than 0.6 degrees Celsius per decade!

Coastal areas around the world are already grappling with the effects of rising seas. Take Bangladesh, for example, where salt is creeping into drinking water. In Norfolk, Virginia, officials and homeowners are dealing with increasingly frequent coastal floods. And the shores of low-lying nations like Tonga are being eaten away by rising waters.

Plant and animal species are declining.

All that with just a 0.8-degree increase! Now consider that we are on track for another 6 degrees Celsius (11 degrees Fahrenheit) of warming by early in the next century — unless we drastically limit carbon pollution from fossil fuels, that is. What would 6 degrees mean for people around the world?

One thing’s for sure: Things aren’t going to get any easier. In fact, a report (PDF) from the National Research Council suggests that for every degree of global warming, the world could see a 3-10% increase in the amount of rain falling in extreme storms, a 5-15% reduction in crop yields, and a 200-400% increase in the area burned by wildfire in the American West.